The present disclosure relates to fuel tank vent valves, and particularly to venting apparatus which operates to seal the vapor space in the interior of a fuel tank at the completion of vehicle refueling to prevent the passage of liquid fuel outside the tank and during refueling and reopens at some point after refueling has been completed to vent the vapor space. More particularly, the present disclosure relates to a buoyant valve arranged to open and close a tank venting outlet passageway.
According to the present disclosure, a tank vent apparatus comprises a valve housing formed to include an interior region, an inlet port, and an outlet port and flow-control means for blocking discharge of fuel vapor admitted into the interior region from the valve housing through the outlet port in response to admission of a predetermined amount of liquid fuel into the interior region through the inlet port. The inlet port is adapted to receive liquid fuel and fuel vapor from a vehicle fuel tank. The outlet port is adapted to discharge pressurized fuel vapor to a fuel vapor treatment canister located outside the fuel tank.
In an illustrative embodiment, the flow-control means comprises a vertical interior wall including a valve seat formed to include a vent port and a vent port valve mounted for up and down movement in the interior region of the valve housing to close and open the vent port. The vent port valve includes a buoyant float located in the interior region of the valve housing to float up and down in liquid fuel admitted into the interior region through the inlet port and a seal coupled at one end to the float and at another end to the vertical interior wall at a point just below the valve seat.
In operation, when the tank vent apparatus is mounted inside a vehicle fuel tank, pressurized fuel vapor in the fuel tank normally passes from the tank into the interior region of the valve housing through the inlet port, through the opened vent port, out of the valve housing through the outlet port, and then on to a fuel vapor treatment canister located outside of the fuel tank. During such normal operation, there is little or no liquid fuel present in the interior region of the valve housing and the float remains in a lowered position pulling the seal downwardly away from the vent port to allow pressurized fuel vapor to flow xe2x80x9claterallyxe2x80x9d through the opened vent port en route to the outlet port.
During refueling, the level of liquid fuel will rise as more and more fuel is pumped into the fuel tank. Eventually, liquid fuel will pass into the interior region of the valve housing through the inlet port and raise the float in the interior region of the valve housing. Such upward movement of the float causes the seal to roll upwardly along the valve seat and close the vent port to block lateral flow of pressurized fuel vapor therethrough so that fuel vapor admitted into the interior region is not able to escape from the interior region through the outlet port.
In an illustrative embodiment, the valve housing includes a top wall adapted to be mounted to a top wall of a fuel tank, a bottom wall positioned to lie in spaced-apart relation to the top wall, and an outer side wall arranged to cooperate with the top and bottom walls to define the interior region. The inlet port is formed in the outer side wall and the outlet port is formed in the bottom wall. The vertical interior wall is cylinder-shaped and coupled to the bottom wall at the outlet port and oriented to extend upwardly toward the top wall so that the vent port is located near to the top wall. The float is ring-shaped and surrounds the cylinder-shaped vertical interior wall. The seal includes a base coupled to the float, a lip coupled to the vertical interior wall, and a pliable annular membrane arranged to interconnect the base and the lip and configured to surround the cylinder-shaped interior wall.
Additional features of the present disclosure will become apparent to those skilled in the art upon consideration of the following detailed description of illustrative embodiments exemplifying the best mode of carrying out the present disclosure as presently perceived.